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The spectrum shift from the sub-6G band to the high-frequency band has posed an ever-increasing demand on the paradigm shift from narrowband beamforming to wideband beamforming. Despite recent research efforts, the problem of wideband…

Computational Engineering, Finance, and Science · Computer Science 2024-07-09 Xiaowei Qian , Xiaoling Hu , Chenxi Liu , Mugen Peng

Reconfigurable intelligent surface (RIS) is regarded as a promising technology with great potential to boost wireless networks. Affected by the "double fading" effect, however, conventional passive RIS cannot bring considerable performance…

Signal Processing · Electrical Eng. & Systems 2022-10-06 Qi Zhu , Ming Li , Rang Liu , Yang Liu , Qian Liu

Space-fed large antenna arrays offer superior efficiency, simplicity, and reductions in size, weight, power, and cost (SWaP-C) compared to constrained-feed systems. Historically, horn antennas have been used for space feeding, but they…

Signal Processing · Electrical Eng. & Systems 2025-05-15 Krishan Kumar Tiwari , Thomas Flisgen , Wolfgang Heinrich , Giuseppe Caire

Large-scale antenna arrays employed by the base station (BS) constitute an essential next-generation communications technique. However, due to the constraints of size, cost, and power consumption, it is usually considered unrealistic to use…

Information Theory · Computer Science 2021-10-28 Kunzan Liu , Zijian Zhang , Linglong Dai , Lajos Hanzo

Active reconfigurable intelligent surface (RIS) emerges as an effective technique to resist the double-fading attenuation of passive RIS. By embedding with power harvesting function, it further evolves to zero-power active RIS, which can…

Information Theory · Computer Science 2025-10-17 Xiao Zheng , Wenchi Cheng , Jingqing Wang , Zhuohui Yao , Jiangzhou Wang

Reconfigurable intelligent surface (RIS)-empowered communication is a revolutionary technology that enables to manipulate wireless propagation environment via smartly controllable low-cost reflecting surfaces. However, in order to…

Information Theory · Computer Science 2022-12-13 Zehra Yigit , Ertugrul Basar , Ibrahim Altunbas

A reconfigurable intelligent surface (RIS) is composed of low-cost elements that manipulate the propagation environment from a transmitter by intelligently applying phase shifts to incoming signals before they are reflected. This paper…

Information Theory · Computer Science 2024-07-23 Mohammad Javad-Kalbasi , Mohammed Saif , Shahrokh Valaee

The emerging reflecting intelligent surface (RIS) technology promises to enhance the capacity of wireless communication systems via passive reflect beamforming. However, the product path loss limits its performance gains. Fully-connected…

Information Theory · Computer Science 2025-03-26 Konstantinos Ntougias , Symeon Chatzinotas , Ioannis Krikidis

Antenna array technology enables directional transmission and reception of wireless signals, for communications, localization, and sensing purposes. The signal processing algorithms that underpin this technology began to be developed…

Signal Processing · Electrical Eng. & Systems 2022-03-09 Emil Björnson , Henk Wymeersch , Bho Matthiesen , Petar Popovski , Luca Sanguinetti , Elisabeth de Carvalho

A reconfigurable intelligent surface (RIS) consists of a large number of low-cost elements that can control the propagation environment seen from a transmitter by intelligently applying phase shifts to impinging signals before reflection.…

Signal Processing · Electrical Eng. & Systems 2023-11-14 Parisa Ramezani , Maksym A. Girnyk , Emil Björnson

Reconfigurable intelligent surface (RIS) provides a promising way to build the programmable wireless transmission environments in the future. Owing to the large number of reflecting elements used at the RIS, joint optimization for the…

Information Theory · Computer Science 2021-01-11 Xiaoyan Ma , Shuaishuai Guo , Haixia Zhang , Yuguang Fang , Dongfeng Yuan

Beamforming plays a crucial role in millimeter wave (mmWave) communication systems to mitigate the severe attenuation inherent to this spectrum. However, the use of large active antenna arrays in conventional architectures often results in…

Signal Processing · Electrical Eng. & Systems 2025-10-08 Mahmoud Raeisi , Hui Chen , Henk Wymeersch , Ertugrul Basar

Reconfigurable intelligent surface (RIS) has emerged as a cost- and energy-efficient solution to enhance the wireless communication capacity. However, recent studies show that a very large surface is required for a RIS-assisted…

Signal Processing · Electrical Eng. & Systems 2021-03-09 Nhan Thanh Nguyen , Quang-Doanh Vu , Kyungchun Lee , Markku Juntti

In this work, we tackle the problem of beampattern design for a transmit system employing a large reconfigurable intelligent surface (RIS) to redirect radio frequency signals emitted by a few active antennas (sources). We begin by…

Signal Processing · Electrical Eng. & Systems 2025-07-15 Ciro D'Elia , Emanuele Grossi , Luca Venturino

Reconfigurable Intelligent Surfaces (RIS) or Intelligent Reflecting Surfaces (IRS) are metasurfaces that can be deployed in various places in wireless environments to make these environments controllable and reconfigurable. In this paper,…

Information Theory · Computer Science 2020-01-22 S. Mohammad Razavizadeh , Tommy Svensson

This letter presents a novel Reconfigurable Intelligent Surface (RIS) that features a low-profile structure, wide operating bandwidth, and continuous phase control. By incorporating a middle patch layer without introducing an additional air…

Signal Processing · Electrical Eng. & Systems 2025-05-13 Yikun Li , Yufei Zhao , Chau Yuen , Xiong Qin , Christ Clenson , Chao Du , Yong Liang Guan

Reconfigurable Intelligent Surfaces (RIS) have been proposed as a revolutionary technology with the potential to address several critical requirements of 6G communication systems. Despite its powerful ability for radio environment…

Signal Processing · Electrical Eng. & Systems 2024-01-09 Yun Yang , Zhiping Lu , Ming Li , Rang Liu , Qian Liu

Reconfigurable intelligent surfaces (RISs) have been deemed as one of potential components of future wireless communication systems because they can adaptively manipulate the wireless propagation environment with low-cost passive devices.…

Signal Processing · Electrical Eng. & Systems 2022-03-23 Yanan Ma , Rang Liu , Yang Liu , Ming Li , Qian Liu

We propose a new reconfigurable intelligent surface (RIS) structure, referred to as interconnected RIS (I-RIS), which allows the RIS elements to be interconnected and share the incident signals using simple binary radio frequency (RF)…

Information Theory · Computer Science 2024-07-17 Sajjad Nassirpour , Naoki Kusashima , Jose Flordelis , Alireza Vahid

While reconfigurable intelligent surface (RIS)-aided user-specific beamforming has been vastly investigated, the aspect of utilizing RISs for assisting cell-specific transmission has been largely unattended. Aiming to fill this gap, we…

Signal Processing · Electrical Eng. & Systems 2023-12-04 Parisa Ramezani , Maksym A. Girnyk , Emil Björnson
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